Object relation theory, formulated by Margaret Mahler in 1975, describes the child's separation and individuation process from the maternal figure, occurring between birth and age 3. The theory includes various phases, such as the autistic phase, symbiotic phase, and separation-individuation phase, which detail key developmental milestones and emotional dynamics between the child and mother. The theory emphasizes the importance of adequate maternal care in fostering the child's healthy growth and emotional development.